player_thread: get "elapsed" from audio outputs

Tracking the "elapsed" time from the chunks which we have sent to the
output pipe is very imprecise: since we have implemented the music
pipe, we're sending large number of chunks at once, giving the
"elapsed" time stamp a resolution of usually more than a second.

This patch changes the source of this information to the outputs.  If
a chunk has been played by all outputs, the "elapsed" time stamp is
updated.

The new command PLAYER_COMMAND_REFRESH makes the player thread update
its status information: it tells the outputs to update the chunk time
stamp.  After that, player_control.elapsed_time is current.

1 files changed, 6 insertions, 0 deletions

diff --git a/src/player_control.h b/src/player_control.h
index 1acdb5686..e9a43e844 100644
--- a/src/player_control.h
+++ b/src/player_control.h
@@ -48,6 +48,12 @@ enum player_command {
 	 * stop
 	 */
 	PLAYER_COMMAND_CANCEL,
+
+	/**
+	 * Refresh status information in the #player_control struct,
+	 * e.g. elapsed_time.
+	 */
+	PLAYER_COMMAND_REFRESH,
 };
 
 enum player_error {